city vs Nanjing

city and Nanjing both are nouns.

Word	Noun	Adjective	Verb	Adverb
city	Yes	No	No	No
Nanjing	Yes	No	No	No

city (noun)	Nanjing (noun)
people living in a large densely populated municipality	a city in eastern China on the Yangtze River; a former capital of China; the scene of a Japanese massacre in the 1930s
a large and densely populated urban area; may include several independent administrative districts
an incorporated administrative district established by state charter